1. Field of the Invention
An embodiment of the invention relates generally to the field of space charge dosimeters. More particularly, an embodiment of the invention relates to space charge dosimeters for extremely low power measurements of radiation in shipping containers.
2. Discussion of the Related Art
The worldwide ocean-going freight transportation infrastructure, known as the Marine Transportation System (MTS), is under stress from several fronts including: terrorism, antiquated technology, environmental restrictions, just-in-time manufacturing practices, overlapping state/federal/local jurisdictions, and a lack of basic technological infrastructure. Terrorist attacks may likely focus on economic terrorism to affect change in the modern world. One need only look to the open movement of containerized cargo to find simple, effective, and efficient means of large-scale economic damage (RFID Journal, 2003). The destruction, or the stoppage of flow at a few key ports could damage our economy and cripple the nation in a matter of weeks (Flynn, 2003). Consequently, there is a need to develop and deploy tracking and monitoring technologies at the container level to help secure the global supply chain and the critical port facilities that service the economic well-being of our nation and other nations (Gills and McHugh, 2002; Bonner, 2002; Verton, 2002).
A port is an assemblage of many facilities, entities and functions including: federal stakeholders (e.g., U.S. Customs, Coast Guard, DOD, TSA, FBI, etc.), state government stakeholders (e.g., Ports Authority, State Law Enforcement, Emergency Preparedness, etc.), and local stakeholders (e.g., local law enforcement, local fire departments, port security, and commercial terminal operators, labor unions, etc.). Developing additional facilities to network the critical components of operations at each port to provide for port security/management and ship/cargo security/tracking/management will aid in efficient use and safety of each port. Ultimately, these local port facilities should be linked to a regional center and/or national center with potential for international expansion. Consequently, there is a need to adopt technologies, such as geographic information systems (GIS), global satellite communications, the internet, and wireless monitoring/tracking/security infrastructure in managing/securing the modern supply chain preferably with an open systems architecture to allow multiple public and private entities to participate.
Shipping via the Marine Transportation System (MTS) totaled $480 billion in cargo and contributed $750 billion to the U.S. gross domestic product in calendar year 1999, and the current volume of domestic maritime shipping is expected to double (USDOT, 1999) over the next 20 years. International maritime shipping is expected to triple over the same time period (Prince, 2001). Many port facilities are under economic stress from the above-noted several fronts, including antiquated technology, environmental restrictions, just-in-time manufacturing practices, overlapping federal/state/local jurisdictions, and the lack of basic technological infrastructure to orchestrate a secure and efficient container management system. In addition, land competition and environmental regulations will restrict the geographic expansion of most current port facilities. The information systems tasked with managing containers are still largely dependent on manual data entry. Consequently, there is a need for automated technology solutions to increase efficiency and security in port facilities (Gills and McHugh, 2002; Verton, 2002; Gillis, 2002).
In addition to concerns about MTS economic inefficiencies, the MTS currently has an unprecedented emphasis on homeland security. In 2001, 5.7 million containers entered the U.S. via the MTS (Gills and McHugh, 2002). U.S. Customs inspects less than 2% of these containers manually, relying on intelligence to “profile” containers. The Coast Guard and U.S. Customs do not have the manpower or resources to manually search each container entering the U.S., and doing so would bring the supply chain to a catastrophic halt (Loy, 2002). Intelligent profiling of cargo and containers is critical to securing the global supply chain and enabling legitimate commerce. Tracking and monitoring would provide better data from which to build intelligent profiles. Therefore, there is a need for investment in appropriate tracking and monitoring technology as the key to increased security and economic efficiency (Flynn, 2003).
A key concern with containerized cargo transportation is the relative ease with which a thermonuclear device or radioactive material for a “dirty bomb” could be smuggled into the target country in a shipping container. A significant specific problem for Homeland Security is the potential shipping of radioactive material for a “dirty bomb” into the United States in a shipping container. The standard marine shipping container has become the dominant method of importing and exporting goods worldwide. The number of containers arriving and departing from US ports each day is so large that only an extremely small fraction is ever inspected. Since only a small fraction of containers can ever be inspected, some method must be employed to “flag” containers for inspection. Locating sensor portals through which each container must pass at each port facility is considered unrealistic. Such a bottle neck could cost the US economy billions of dollars each day. Employing a radiation sensor in, on or near the cargo container to look for elevated levels of radiation would be one method of flagging containers.
However, there are problems with existing radiation sensors that have been proposed for shipping containers. First, existing radiation sensors must use power during the dose integration (active sensing) time. Existing active radiation sensors must either utilize very short integration times, thus reducing sensitivity, or they will use up their available battery power long before the end of the service life of the container. Replacing batteries requires maintenance personal time, coordination between the maintenance schedule and the physical location of the container and logistical support. There is a need for radiation sensors with a much longer unattended service life.
Second, existing active radiation sensors do not make the dose integration data available for secure and uninterrupted monitoring of the each container. Reading the dose integration data requires that the individual sensors be removed and read, or at least individually read, leading to the same problems of costly maintenance personal time, coordination between the data collection schedule and the physical location of the container and logistical support. There is a need for radiation sensors that make the dose integration data automatically and remotely available for intelligent profiling and analysis.
Third, existing active radiation sensors are prone to false alarms. Existing active radiation sensors cannot discriminate between different types of radiation leading to false alarms from substances used for medical diagnosis and even from benign cargo such as bananas which naturally contain concentrations of ionizing radiation substances (e.g., potassium). There is a need for more sophisticated and discriminatory radiation sensors.
Heretofore, the requirements of container-level tracking and monitoring by long-life sensors, making the critical data automatically and remotely available for intelligent profiling and analysis and reducing false alarms have not been met. What is needed is a global container security and asset (ship and cargo) tracking system that satisfies (preferably simultaneously all of) these requirements.